Remote center compliance (RCC) devices provide a remote center of compliance at, near, or beyond the free end of an operator means or member. The operator member, with the remote center near its tip, may perform or carry parts that perform various functions, e.g. docking, tooling, insertion, engaging. The remote center of compliance is a point about which rotation of the operator member occurs and with respect to which translation of the operator member occurs. RCC devices have five major degrees of freedom, rotation about the axis of the operator member, and rotation and translation along two mutually perpendicular lateral axes orthogonal to the axis of the operator member. The RCC device is a passive device and translations and rotations are the result of forces and torques applied during operation. The translations and rotations may be in any combination, depending upon the specific compliance of the RCC device and the applied load, within the range of the physical limits of the RCC device.
Determination of the axial force applied to an RCC device is an important and useful function. Any particular RCC device has a limit beyond which the RCC device may be damaged. Additionally, the members with which the RCC device engages or cooperates are often delicate or require delicate insertion or contact forces which it would be well to monitor. Even in more rugged RCC device operations where heavy loads are applied, the monitoring of elevated axial forces is a valuable feature. Previously, force detection was available through force sensors which were of relatively delicate construction to permit sensing of small, as well as large, forces. Such sensors had to be coupled to the RCC device through means of generally heavy, large couplings. One solution for the protection of the RCC, the workpieces, or the sensor provided a spring-locked station to hold the work addressed by the RCC device. The station used a spring loaded table set to give way in order to protect the RCC device and the workpiece when the force exceeded a safe threshold.